Break dancing is a popular activity in teenagers and is associated
with severe trauma to bones and tissues. We report the first known case
of a break dancer with an ulnar stress fracture. Such injuries occur in
a variety of sports due to substantial stress on the ulna and repetitive
excessive rotation of the forearm. In this study we describe a patient
who experienced an ulnar stress fracture during break dancing training.
The diagnosis was established by history and physical examination.
Initial radiographic findings were negative. However, radiographs taken
3 months after initial presented revealed callus formation over the
ulnar shaft. This suggested that readjustment is required in break
dancing training protocols. It is important to increase awareness of
this injury among physicians to expedite the diagnosis and to prevent
the possibility of conversion to an overt fracture in the future.

Break dancing has been a potentially dangerous form of recreation
since its appearance in popular American culture in the late 1980s. Many
fundamental break dancing moves require support of body weight by the
hands and arms as the feet and legs move the body around an axis. Severe
bone and tissue trauma have described in many cases in the medical
literature (Goscienski and Luevanos, 1984). To our knowledge, this is
the first identified case of an ulnar shaft stress fracture in a break
dancer.

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Case history

A 16-year-old male patient reported right forearm pain of 3 weeks
duration during preparation for an upcoming break dancing performance.
The pain was most pronounced during right forearm rotation and right
wrist extension. The patient taped the arm for 4 to 5 days for increased
support and did not take pain medication. The patient increased his
daily practice time to a daily total of 6 hours, particularly for the
hand glide position. This position included a spin on the right hand
supporting the entire body weight with torsional stress present on the
right forearm (Figure 1). His pain became so severe during the
performance that he was unable to support his body weight on the right
arm. A visible swelling subsequently developed in the forearm.

Physical exam findings on clinical presentation included mild
tenderness on right wrist palpation and significant tenderness over the
middle third of the ulnar shaft. The patient reported increased pain
upon resisted dorsal flexion of the wrist and significantly increased
pain with a fulcrum-type ulnar valgus stress. Initial radiographic
findings were insignificant (Figure 2A).

The clinical history and presentation were strongly suggestive of a
stress fracture of the middle third of the ulnar shaft. The patient was
advised to restrict both weight bearing and rotational physical
activities of the right forearm. Follow-up radiographs after 3 months
revealed solid callus formation on the medial aspect of the middle third
of the ulnar shaft (Figure 2B). The right arm was able to bear full body
weight in the hand glide position at 6 months after treatment (Figure
1).

The clockwise spin performed in the hand glide position while
balanced in a right-handed float position resulted in at least 3 causes
of stress. First, wrist hyperextension resulted in contraction forces at
the middle third of the ulnar shaft at the insertion sites of the
extensor carpi ulnaris and extensor pollicis longus. Next, one-handed
standing positions results in compression forces through the rotation
center axis of the forearm from the radial head to the distal ulna
(Nakamura et al., 1999) with full body weight. Lastly, clockwise
right-handed spins resulted in torsion forces over the middle third of
the ulnar shaft when radial position around the ulna shifted from
supination to pronation (Nakamura et al., 2000). A previous study by
Tanabe et al. found that the ulnar rotation was retricted with the small
rotation range of the brachioulnar and distal radioulnar joints and
allowed a strong radial revolving force during forceful pronation and
acted on the ulna. Morphologic studies indicated that the
cross-sectional area of the middle third of the ulna was
triangular-shaped, smaller, and had thinner cortices than other parts of
the bone. These findings implied that stress fractures readily developed
in the middle third of the ulna when the ulnar shaft sustained excessive
torsion forces (Tanabe et al., 1991).

The upper extremities are frequently used to support body in both
gymnastics and in break dancing. Events such as the pommel horse, floor
exercise, and balance beam include many elements that result in
recurrent loading of the upper limbs with relatively large static and
dynamic forces. To our knowledge, this is the first stress fracture of
the ulnar shaft associated with break dancing in the medical literature.
Unlike gymnastics, break dancing is usually carried out without
supervision. Although break dancing is very appealing to children and
teenagers it frequently lacks suitable venues and training (Johnson and
Jones, 1986). Break dancing moves are associated with sudden increases
in loads and frequencies of training, and is strongly associated in
ulnar stress fractures. Other examples include large weight increases
during training in weight lifters and increasing training length times
in tennis and tennis and table tennis players (Hamilton, 1984; Rettig,
1983). The patient added 2 to 4 hours of extra training per day for 2
weeks prior to break dancing performances, and this may have contributed
to the injury.

The biomechanical loading, poor training courses, and overtime
activity of break dancing combined with anatomic weakness, and this
collectively resulted in a stress fracture of the middle third of the
ulna in this patient. Plain radiographs are diagnostically useful when
positive, but generally have low sensitivity. Radionuclide bone scanning
is highly sensitive, but lacks specificity and the ability to directly
visualize fracture lines. Magnetic resonance imaging (MRI) provides
highly sensitive and specific evaluation for bone marrow edema and
periosteal reaction as well as for the detection of subtle fracture
lines. However, MRI is expensive and does not contribute to further
clinical management. A thorough clinical history, complete physical
examination, and plain radiography comprised the diagnostic work-up in
this patient. Bone scans and MRI studies are useful when plain
radiographs are equivocal and a definitive diagnosis is required
rapidly. Our data suggest that some readjustment is required in the
training protocol for break dancers to minimize and prevent the
likelihood of ulnar stress fractures.

Conclusion

Break dancing is a widely practiced activity with unique physical
demands and associated medical problems. A clinical history of break
dancing may change or enhance a differential diagnosis, even in
non-orthopedic settings. The patient's clinical history and
physical examination were initially used to diagnose a stress fracture
despite a normal radiographic study, and this early diagnosis may have
prevented conversion to an overt fracture.

Key points

* Stress fractures should not be ignored when the patient changes
exercise loading.

* A thoroughly detailed clinical history, physical examination, and
plain radiographs were used diagnostically in this clinical case.

* The best methods for the treatment of stress fractures include
readjustment training protocols to prevent conversion to overt
fractures.